Automatic pressure control of sugar cane mills



J. N. EDWARDS AUTOMATIC PRESSURE CONTROL OF SUGAR CANE MILLS Oct. 12, 1954 Filed 0ct 1 2, 1949 INVENTOR ATTORNEYS F! p: H

Patented Oct. 12, 1954 AUTOMATIC PRESSURE CONTROL SUGAR CANE MILLS.

Joseph N. Edwards, New Orleans, La., assignor to Edwards Engineering Corporation, New GI- leans, La., a corporation of Louisiana Application October 12, 1949, Serial No. 120,838

7 1 Claim. (Cl. 100-170) v i i v 1.

This invention relates to roll mills for crushing and pressing sugar cane to extract juice for use in the manufacture of raw sugar. In this type of mill the cane or other fibrous sugarcontaining stalks are crushed and pressed by passing them over a pairof rolls and beneath anupper floating pressure roll having a tiltable axis. and coacting with both of said pair to apply, the desired crushing and juice extracting pressure to the cane. In the usual type of such mills the three rolls are connected by a pair of crown gears secured to the lower rolls, and both meshing with. a gear on the'upper roll so that the rolls and gears are connected in series, with power applied to one of the crown gears.

As the thickness of the mat of cane varies both across the width of the mat and lengthwise thereof, and as it is desired to maintain a substantially constant pressure on both ends of the upper. roll, the latter is so mounted that it and its bearings may have vertical and tilting movements, in accordance with varying thicknesses of the mat of cane. To permit such vertical movement, and at the same time to maintain a yielding pressure on the upper roll, it has been proposed to apply downwardly acting fluid pressure on rams engaging the bearings of the upper roll. See for instance the patents to Nadler 1,978,218, Munson 2,101,266, and Schwarz 2,205,632.

As the rolls are connected at one end only by the gears, the resistance to rotation of the upper and floating roll causes the driving gear to exert a thrust on the geared end of the upper roll and liftthe latter so that it exerts a lesser pressure on the mat at the geared end portion than on the other end.

The mainobject of the present invention is to provide means whereby the pressure on the matis maintained substantially constant at the opposite ends of the upper or floating roll, and therefore, from a'practical standpoint throughout the length of the roll. This is accomplished by providing independent means free of inertia and friction for automatically maintaining constant pressure on the rams, with the pressure at the gear driven end greater than at the opposite end, thereby to compensate for the upward thrust of the gears and to insure uniform pressure on'the mat of cane.

A further object is to provide means whereby the pressure on the upper or floating roll remains substantially constant, irrespective of variations in the distance to which the upper roll lowers or is forced upwardly during the delivery of a mat of. varying thickness.

A further object is to provide means whereby any desired difference in pressure may be maintained on the bearings at the ends of the upper or floating roll, and compensate for the upward thrust exerted by the crown gears.

A further object is to provide means for applying pressure on the upper or floating roll, and

which is small, compact, safe, self-sealing, moisture and dust proof, and which does not require any maintenance.

In carrying out my invention I provide one or more hydro-pneumatic accumulators, each having a casing providing two chambers separated by a flexible and expansible diaphragm or bag, which prevents any mixing of the oil and gas. One of these contains a non-compressible liquid acting on the rams, and the other contains a gas under high pressure, providing a dynamic force on the diaphragm and on the liquid. The chambers are of such relative sizes that normal variations in the volume of the liquid in the chambers, due to the raising and lowering of the rams, do not change the gas pressure to any substantial extent. Thus, the ends of the upper roll may rise to different distances, and in doing so force different amounts of liquid into the corresponding liquid chambers and against substantially uniform pressure in the gas chambers; but substantially equal pressures will be exerted on the opposite ends of the upper roll during normal bodily raising or lowering of the, roll, or the raising of one end in respect to the other end.

The casings may be mounted on the rams with their liquid chambers directly connected to the chambers of the rams, or they may be connected by small diameter flexible copper tubing, and thus the liquid and gas containing chambers may be conveniently located at any desired distance from the mill. There may be a large number of such casings grouped together and connected to tubing extending to the rams of different mills.

Where tubing is used, it may be of predetermined internal diameter and length, and the.

liquid may be of predetermined viscosity, so that momentary predetermined automatic increase in pressure on the rams may be obtained by the back pressure developed, thus compensating for increase in the volume or consistency of the feed.

By means of the present invention it has been established that the extraction of sucrose from the cane is appreciably increased and the moisture content of the bagasse is lowered, due to the freedom of vertical movement of the upper rolls or the ends thereof, and under uniform pressure;

sure on any one or all of the accumulators and rams simultaneously.

When accumulators A, B, C and D are hydraulically charged by the pump 39 to the desired pressure, valves 33, 34, 35 and 39 are electrically or manually closed, thus providing a closed hydraulic circuit between the accumulators and the rams. To create a greater pressure on the rams at the geared ends of the mills, liquid may be pumped in through a pipe 38 from a pump 39 driven by a motor 630. By opening the valve ii and any one or all of the valves 33, 34, 35 and (it, liquid may be discharged from the accumulators, or the desired one of them, and returned through pipe 92 to a tank 23, from which the pump 39 draws its supply through a pipe 44 and filter 95.

By opening a valve is liquid may be transferred from the spare accumulator E to the desired one of the other accumulators.

In case of bag rupture or any other failure of one of the accumulators A, B, C or D, the liquid may be drained from that one and from accumulator E, and the latter removed and substituted for the defective one. The building up of an undesirably high pressure in the accumulators and the rams being charged may be prevented by an automatic relief valve 41. It will be understood that when an accumulator is to be removed for any purpose, the liquid is drained out until the bag expands to close the check valve 25 and another accumulator is secured in place and the pressure raised by pumping in more liquid. Suitable pressure gauges are connected to the rams or the pipes leading to them, so that the desired higher pressure on the geared end of the mill may be obtained by pumping additional liquid into the accumulator connected to those ends. When operating the rams, no safety or relief valve is required on the accumulators on the rams, as the liquid and gas displacement of the accumulators is several times the liquid displacement in the ram cylinder l6.

It will be understood that in a simplified embodiment of my invention all of the piping, the pump and the reservoir may be omitted, and the threaded nipples 26' of the accumulators may be screwed into ram cylinders It When the upper roll I2 is in its lowermost position and the cylinder of the ram later filled with the pressure-transmitting liquid by means of a suitable hydraulic pump. The spare accumulator may be used to supply hydraulic pressure to other parts or apparatus in the factory, as it has a separate valve controlled pipe 49.

The piping for the pressure gauge and for con ducting the liquid to the ram cylinder may be attached directly to the nipple as shown in Fig. 3, or may be branched from a pipe or tube secured to the end of the nipple 26 as indicated in Fig. 1.

By reason of the relatively large volume of the air on one side of the diaphragm or bag wall, and the high pressure on it, any slight leakage of the oil or other liquid from the system will be compensated for by slight expansion of the bag, which does not materially reduce the pressure, or additional liquid may be pumped in from time to time to reduce the size of the bag and restore the pressure desired. The operator may thus increase or decrease the pressure on either or both ends of the mill at any time by pumping in or bleeding off liquid from the accumulator.

In my improved system, no safety valves or paclrings are required, and the spare accumulator may be quickly removed and substituted for any one of the others which may develop any trouble. The pump need be used only at rare intervals, and when operating, its pulsations are cushioned by the high pressure gas.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

A sugar cane roll mill having a pair of rolls rotatable about fixed axes and a superposed floating roll, said rolls being connected by gears at one end only thereof, means for rotating one of said pair of rolls and thereby rotating the other two through said gears, a pair of vertically movable bearings for the ends of said third roll, each bearing connected to a piston, a cylinder for each pis-v ton, and means for maintaining substantially constant pressure on both of said pistons, said means including a pair of casings each having a flexible diaphragm with gas under high pressure at one side thereof and a liquid on the other side thereof, each liquid side of the casings of said pair being individual to and connected with one of said cylinders, whereby upward movement of the ends of said superposed floating roll is resisted by substantially constant gas pressure through the medium of the pressure liquid separated from said gas under pressure by said flexible diaphragm, whereby said superposed floating roll is maintained under substantially constant and substantially equal pressure at its ends, notwithstanding the upward thrust exerted by said gears and the changing thickness of the mat of sugar cane passing through said rolls while said mill is running.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 497,301 Buchel May 16, 1893 974,349 Bowen Nov. 1, 1910 1,259,393 Graham Mar. 12, 1918 1,808,356 Kleinewefers June 2, 1931 1,819,290 Hegenbarth Aug. 18, 1931 1,852,435 Ritchie Apr. 5, 1932 1,978,218 Nadler Oct. 23, 1934 2,204,434 Munson June 11, 1940 2,205,632 Schwarz et al June 25, 1940 2,331,921 Mercier Oct. 19, 1943 2,385,016 Mercier Sept. 18, 1945 

